﻿/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Velocity4Net.Ctx;
using System.Collections;

namespace Velocity4Net
{
    /// <summary>
    ///  General purpose implemention of the application Context
    ///  interface for general application use.  This class should
    ///  be used in place of the original Context class.
    ///
    ///  This implementation uses a HashMap  (@see java.util.HashMap )
    ///  for data storage.
    ///
    ///  This context implementation cannot be shared between threads
    ///  without those threads synchronizing access between them, as
    ///  the HashMap is not synchronized, nor are some of the fundamentals
    ///  of AbstractContext.  If you need to share a Context between
    ///  threads with simultaneous access for some reason, please create
    ///  your own and extend the interface Context
    /// 
    ///  @see org.apache.velocity.context.Context
    ///
    ///  @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
    ///  @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
    ///  @author <a href="mailto:fedor.karpelevitch@home.com">Fedor Karpelevitch</a>
    ///  @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
    ///  @version $Id: VelocityContext.java 898032 2010-01-11 19:51:03Z nbubna $
    /// </summary>
    public class VelocityContext : AbstractContext
    {
        /**
         *  Storage for key/value pairs.
         */
        private Hashtable context = null;

        /**
         *  Creates a new instance (with no inner context).
         */
        public VelocityContext()
            : this(null, null)
        {
        }

        /**
         *  Creates a new instance with the provided storage (and no inner
         *  context).
         * @param context
         */
        public VelocityContext(Hashtable context)
            : this(context, null)
        {
        }

        /**
         *  Chaining constructor, used when you want to
         *  wrap a context in another.  The inner context
         *  will be 'read only' - put() calls to the
         *  wrapping context will only effect the outermost
         *  context
         *
         *  @param innerContext The <code>Context</code> implementation to
         *  wrap.
         */
        public VelocityContext(IContext innerContext)
            :
                 this(null, innerContext)
        {
        }

        /**
         *  Initializes internal storage (never to <code>null</code>), and
         *  inner context.
         *
         *  @param context Internal storage, or <code>null</code> to
         *  create default storage.
         *  @param innerContext Inner context.
         */
        public VelocityContext(Hashtable context, IContext innerContext)
            : base(innerContext)
        {
            this.context = (context == null ? new Hashtable() : context);
        }

        /**
         *  retrieves value for key from internal
         *  storage
         *
         *  @param key name of value to get
         *  @return value as object
         */
        public override Object InternalGet(String key)
        {
            return context[key];
        }

        /**
         *  stores the value for key to internal
         *  storage
         *
         *  @param key name of value to store
         *  @param value value to store
         *  @return previous value of key as Object
         */
        public override Object InternalPut(String key, Object value)
        {
            context[key]=value;
            return value;
        }

        /**
         *  determines if there is a value for the
         *  given key
         *
         *  @param key name of value to check
         *  @return true if non-null value in store
         */
        public override bool InternalContainsKey(Object key)
        {
            return context.ContainsKey(key);
        }

        /**
         *  returns array of keys
         *
         *  @return keys as []
         */
        public override ICollection InternalGetKeys()
        {
            return context.Keys;
        }

        /**
         *  remove a key/value pair from the
         *  internal storage
         *
         *  @param key name of value to remove
         *  @return value removed
         */
        public override Object InternalRemove(Object key)
        {
            object o = context[key];
            context.Remove(key);
            return o;
        }

    }

}
